ASA防火墙Dynamic NAT配置

Posted 2020-10-29

说明：
OUTSIDE模拟外网：e/0接口IP：200.200.200.200/24，lo0:8.8.8.8/32，lo10:114.114.114.114/32
INSIDE模拟内网：vlan 10：10.10.10.1/24，vlan 20:10.10.20.1/24，vlan 30:10.10.30.1/24；默认路由指向ASA防火墙-10.10.10.2。
ASA防火墙默认路由指向OUTSIDE-200.200.200.200，10.0.0.0/8下一跳指向INSIDE-10.10.10.1。

需求：INSIDE-10.10.10.0/24需要访问外网（8.8.8.8）
方法一：动态NAT
1.新建network object
2.在object下做NAT（使用外网接口地址做转换）

object network INSIDE-10.10.10.0
subnet 10.10.10.0 255.255.255.0
nat (inside,outside) dynamic interface
exit

access-list OUT-TO-INSIDE extended permit ip any 10.10.10.0 255.255.255.0 //模拟器需要作此策略，真实设备不需要
access-group OUT-TO-INSIDE in interface outside //模拟器需要作此策略，真实设备不需要

测试
INSIDE#ping 8.8.8.8 source vlan 10
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 8.8.8.8, timeout is 2 seconds:
Packet sent with a source address of 10.10.10.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/2 ms

查看ASA防火墙的NAT转换：
ASA(config)# show xlate
1 in use, 3 most used
Flags: D - DNS, e - extended, I - identity, i - dynamic, r - portmap,
s - static, T - twice, N - net-to-net

ICMP PAT from inside:10.10.10.1/22 to outside:200.200.200.1/22 flags ri idle 0:00:01 timeout 0:00:30

方法二：动态NAT
1.新建network object
2.在object下做NAT（使用单独的外网IP做转换）

object network INSIDE-10.10.10.0
subnet 10.10.10.0 255.255.255.0
nat (inside,outside) dynamic 200.200.200.10
exit

access-list OUT-TO-INSIDE extended permit ip any 10.10.10.0 255.255.255.0 //模拟器需要作此策略，真实设备不需要
access-group OUT-TO-INSIDE in interface outside //模拟器需要作此策略，真实设备不需要

测试：
INSIDE#ping 8.8.8.8 source vlan 10
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 8.8.8.8, timeout is 2 seconds:
Packet sent with a source address of 10.10.10.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/4/7 ms

ASA# show xlate
1 in use, 4 most used
Flags: D - DNS, e - extended, I - identity, i - dynamic, r - portmap,
s - static, T - twice, N - net-to-net

ICMP PAT from inside:10.10.10.1/27 to outside:200.200.200.10/27 flags ri idle 0:00:00 timeout 0:00:30